The present invention relates generally to a camera system, and more particularly, is directed to a camera system equipped with both a lens shutter and a focal-plane shutter.
Cameras equipped with a lens shutter and cameras equipped with a focal-place shutter are well-known.
A camera equipped with a lens shutter is adapted for flash photography because of the shape of the shutter opening. On the other hand, the lens of a camera equipped with a focal-place shutter can be replaced because of the light-blocking structure of the focal-plane shutter. In addition, the lens of a camera equipped with a focal-plane shutter permits high-speed time control because of the manner of operation thereof.
In an attempt to combine the features of the aforementioned two cameras, it has been proposed to use an interchangeable lens having a lens shutter in a camera equipped with a focal-plane shutter. In such case, the lens shutter operates as an interchangeable lens, alone and independently of the focal-plane shutter. Because of such independent operation, separate control sections are installed in the camera for the focal-plane shutter and the lens shutter, respectively. However, the use of two separate control sections becomes complicated, costly and wasteful.
Further, it is known that the brightness of a subject to be photographed can be controlled by a lens shutter up to an exposure value (EV or LV) of approximately LV17 or EV17. In other words, it is difficult for a lens shutter to operate at high speeds. This is because diffraction is created by the lens when the size of the aperture is reduced.
Thus, in cameras having a lens shutter, the brightness limit of approximately LV17 is set in the camera such that exposure comparable to a pin hole is not provided. Consequently, when the brightness of the subject to be photographed exceeds the aforementioned limit, no appropriate exposure value is obtained. In such case, when the brightness level exceeds the aforementioned limit of the lens shutter, the lens must be replaced with an interchangeable lens incorporating only a diaphragm. Accordingly, photographs are taken while utilizing the combination of the high-speed operation of the focal-plane shutter and the replaced lens. However, it is difficult and cumbersome to perform a photography operation in such circumstances.
It is also known to provide a camera equipped with a zoom lens and a multifocus lens, that is, with the multifocus lens including a telephoto (long-focus length) lens and a wide-angle (short-focus length) lens. When the telephoto lens is used, the image of the subject is enlarged so that only the region in which the photographer has an interest is photographed. However, with a telephoto lens, the f-number increases, thereby darkening the lens. As a result, the diaphragm must be opened or the shutter speed must be lowered to provide adequate exposure. It is also noted that the use of a telephoto lens shortens the slowest shutter speed at which camera shake will not pose a problem. For example, when a lens has a focal length of 100 mm, the shutter speed will be approximately 1/100 second. When the shutter speed is lower than this value, camera shake will blur the photograph.